Construction for transformer



y 1955 A. E. FEiNBERG CONSTRUCTION FOR TRANSFORMER Filed Jan. 21, 1952 m EN %N m United States Patent CONSTRUCTION FOR TRANSFORMER Albert E. Feinberg, Chicago, Ill.

Application January 21, 1952, Serial No. 267,350

5 Claims. (Cl. 315138) This invention relates generally to transformers and more particularly is concerned with a novel transformer for use as a ballast, functioning to provide the ignition voltage for a plurality of gaseous discharge devices connected in circuit therewith, and, after ignition of the said devices, to provide the operating voltages for the said devices.

The instant invention principally relates to the particular construction of transformer core for use in connection with certain apparatus claimed and described in a copending application, filed jointly by the applicant herein and Paul Berger, filed May 5, 1950, Serial No. 160,366, entitled Apparatus for Igniting and Operating Gaseous Discharge Devices. To that extent this application is a continuation-in-part of the said co-pending application. The core construction generally referred to, but not claimed in the said co-pending application, is the sole invention of the applicant herein.

The principal object of the invention is to provide a novel transformer core having a single magnetic circuit with suitable flux paths and shunts to be associated with a circuit for igniting and thereafter operating a plurality of gaseous discharge devices.

Other objects of the invention lie in the provision of a transformer core of great simplicity, economy, and efiiciency, and one which will provide a good wave shape to current flowing through the gaseous discharge devices.

Many other objects will occur to these skilled in the art to which the invention appertains as the description thereof proceeds in connection with which there has been illustrated and described a preferred embodiment.

In the drawing:

Fig. 1 is a plan view of the transformer of the invention, the windings thereof being shown schematically and in proper association therewith.

Fig. 2 is a diagrammatic view of a circuit suitable for use with the transformer.

Fig. 3 is a fragmentary view of a portion of a modified form of the invention.

The invention rests in the combining of cores for a plurality of gaseous discharge devices, and providing a core which is smaller, more compact, and easier to manufacture than would be the cores for apparatus for a plurality of gaseous discharge device, were said cores made in the conventional manner. Thus, for a four device circuit, it has been customary to provide two transformer cores with two magnetic circuits, and the attendant expense and weight. For a three device circuit, the practice has been to provide two transformers also.

The reference character 10 designates generally the transformer of the invention herein. Same comprises an outer rectangular shell 11 having an elongate formation formed with parallel long sides 12, and bridging end portions 13. The end portions 13 are provided with seating recesses 14 to receive the mating ends of the central winding leg 15. The central winding leg is intended to have the various windings mounted thereon and then is assembled by being forced into the shell 11.

The long sides 12 each have inwardly extending lugs 16, 17, and 18 which are to form magnetic shunts between windings and thereby provide winding windows 19, 20, 21, and 22. The lugs 16 and 18 each terminate short of the sides of the central winding leg 15 to form nonmagnetic gaps 23 and 24. The lugs 17, however, are about half as short as the others, and the sides of the winding leg 15 are provided with integrally formed extensions 25 which meet the shortened lugs 17 to form the non-magnetic gaps 26 thereat. This aids in positioning windings on leg 15.

It will be seen throughout that the amount of steel used in the transformer 10 is a minimum. The view of Fig. 1 shows the outline of a single lamination, the transformer core is formed by stacking a number of laminations in a manner well known and fastening same together by rivets 27. The winding leg 15 is also formed of a stack of laminations riveted together by rivets 29. In the fabrication of the laminations, the winding leg laminations are the punched out centers of the shell laminations, the gaps being formed by shaving.

The identical transformer described can be formed in a slightly diiferent manner as shown in Fig. 3 by providing a central winding leg 15 which is rectangular and extends the entire length of the ballast. The outer shell 11 is re placed by a pair of inwardly directed core members 11' which are identical in configuration to the upper and lower portions of the shell 11. The same shunts, windows, and gaps are formed in the resulting core, and the core is held in assembly by any suitable means such as clamping members symbolically illustrated at 30.

The circuit which is suitable for use with the transformer cores 10 or 10 is illustrated schematically in Fig. 2. The primary P is energized from an A. C. line 31.

' The primary P serves two separate and distinct circuits,

but the circuits all use the same magnetic core and cooperate to provide good power factor and wave shape.

One circuit can be described as a seriatim starting series operating, leading circuit. It ignites and operates the lead lamps LCi and LCz. The other circuit could be also a seriatim starting, series operating circuit of a type illustrated in said co-pending application above referred to, but here is a simple connection of a lamp LL adapted to be ignited and operated by an auto-transformer arrangement. Since the transformer or ballast which normally would be usedin igniting and operating even a single lamp would be about the same size and weight as one which would serve two lamps, it is immaterial whether this invention eliminates the one or the other. The saving is just as great. The transformer core of the invention has been found ideally suited for use with the particular circuit illustrated. I V I The first sub-circuit comprises the primary P cooperating with the windings S1, S2, and S2. Note that windings P, S1, S2, and S2 are connected end to end in the order named, that the lamp M31 and a series condenser C are connected across S1 and P together, while the second lamp LCz is connected across the three secondaries together. S1 is a winding of fine wire and many turns, and is considered the auxiliary starting secondary. it is a high leakage reactance winding, and in order to develop such leakage reactance, it is placed in the window 19, separated from the remainder of the transformer by the shunt formed of lugs 16 and gaps 23. it and the primary P, which is placed in window 2%, develop sufiicient voltage.

during starting to ignite the lamp .LCi. When current flows there is a component of voltage developed in S; which combines with S2 to ignite lamp LCz. Since the coupling between S2 and P is necessarily loose, but not loose as that between 81 and P the shunt formed by lugs 17 and gaps 26 cooperating with extensions 25 is not as 

